The cross-linking, or curing, of polymers has been known for many years. Cross-linking, or curing, creates a three-dimensional structure covalently bridging the polymer chains that in general provides strength and stability to the polymer. The cross-linking of polymer systems is typically carried out by means of radiation (e.g. electron beam radiation) or by addition of suitable curing agents, e.g. the addition of sulphur in the vulcanization of rubber.
It has now been found that compounds comprising at least one 1,5-enediyne moiety can be used as curing agents in polymeric systems.
Compounds comprising a 1,5-enediyne moiety have been described as monomers for the preparation of highly conjugated polymeric networks for use in electronic applications. For instance US 2008/0116452 and US 2007/0120120 both disclose semiconductor thin films obtained by homopolymerizing aromatic enediynes derivatives.
Similarly, U.S. Pat. No. 6,121,495 discloses coatings and laminates comprising at least one layer obtained from polymers derived from the polymerization of ethynyl-substituted aromatic compounds of formula (R—C≡C)nAr-L-[Ar(C≡C—R)m]q wherein each Ar is an aromatic group; each R is independently an alkyl, aryl; L is a covalent bond or group that links one Ar group to at least one other Ar group; n and m are integers of at least 2; and q is an integer of at least 1.
C. R. Hickenboth, J. D. Rule, J. S. Moore, Tetrahedron, 64 (2008), 8435-8448 discloses copolymers comprising recurring units derived from methyl methacrylate and monomers comprising a 1,5-enediyne moiety having methyl methacrylate functional groups. The 1,5-enediyne moiety is incorporated into the poly(methyl methacrylate)polymeric chain by means of the methyl methacrylate functionality. The copolymer comprising the 1,5-enediyne moieties is used as a radical initiator to promote the polymerization of additional methyl methacrylate monomeric units providing a cross-linked polymeric network. No disclosure is made of a composition comprising a polymer on one side and a compound comprising a 1,5-enediyne moiety on the other side.
None of the prior art documents discloses the use of 1,5-enediyne compounds as curing agents in polymeric systems.